Process for making propylene-based copolymer

Abstract

The invention relates to a process for production of copolymers, in particular for the polymerization of propylene, and another monomer chosen from a group comprising ethylene and a C4-C12 α-olefin in a horizontal stirred reactor comprising an agitated bed and several reaction zones for forming polymer particles.

Claims

1. A process for production of a propylene based copolymer, comprising: propylene, a comonomer selected from ethylene or a C4-C12 α-olefin, wherein the said process is performed in the presence of a catalyst system in a horizontal stirred reactor (100) comprising: an agitated bed for forming polymer particles, a plurality of liquid feed ports (111, 112) that are subsequently arranged along a top side of the reactor above the agitated bed, the plurality of liquid feed ports comprising at least a first set of the liquid feed ports (111) and a second set of the liquid feed ports (112) arranged subsequent to the first set of the liquid feed ports in a downstream direction of the process, and a plurality of gas feed ports (114, 115) that are subsequently arranged along a bottom side of the reactor below the agitated bed, the plurality of gas feed ports comprising at least a first set of gas feed ports (114) and a second set of gas feed ports (115) arranged subsequent to the first set of gas feed ports in the downstream direction of the process, a plurality of reactor off-gas ports (116) that are arranged along a top side of the reactor above the agitated bed, wherein the process comprises the steps of: recovering a reactor off-gas (117) comprising H.sub.2, propylene, and comonomer from the reactor through the reactor off-gas ports (116), feeding the reactor off-gas (117) to a condenser (150) to form a gas-liquid mixture (118), feeding the gas-liquid mixture (118) to a separator (140) to obtain a first gas stream (121) and a first liquid stream (119): the first gas stream (121) comprising: H.sub.2, propylene, and the comonomer when it is ethylene and the first liquid stream (119) comprising: H.sub.2, propylene, and the comonomer when it is selected from a C4-C12 α-olefin, wherein fresh propylene is optionally further fed to the system, through the separator (140) and/or added to the first liquid stream (119), feeding the catalyst system to the reactor through a port arranged on the top side of the reactor, feeding a H.sub.2 poor quench liquid (101) comprising propylene through the first set of the liquid feed ports (111), feeding a H.sub.2 rich quench liquid (103) comprising: H.sub.2, propylene, and the comonomer, to the reactor through the second set of liquid feed ports (112), wherein the H.sub.2 rich quench liquid (103) comprises at least part of the first liquid stream (119), feeding a H.sub.2 poor bottom gas (102) comprising fresh propylene through the first set of gas feed ports (114), feeding a H.sub.2 rich bottom gas (104) comprising: H.sub.2, propylene, and the comonomer, through the second set of gas feed ports (115), wherein the H.sub.2 rich bottom gas (104) comprises at least part of the first gas stream (121), and collecting the polymer particles formed in the agitated bed from the reactor, wherein the said process comprises the further following steps: the comonomer, when it is ethylene, is fed to: the reactor as a part of the H.sub.2 poor bottom gas (102) and/or as part of the H.sub.2 rich bottom gas (104) and/or fed to the separator (140); the comonomer when it is chosen from a group comprising a C4-C12 α-olefin, is fed: to the reactor as: a part of the H.sub.2 poor quench liquid (101) and/or a part of the H.sub.2 rich quench liquid (103) and/or to the separator (140).

2. The process according to claim 1, wherein the said comonomer is ethylene.

3. The process according to claim 1, wherein the said comonomer is selected from a C4-C12 α-olefin.

4. The process according to claim 3, wherein the said comonomer is 1-butene.

5. The process according to claim 3, wherein the said comonomer is 1-hexene.

6. The process according to claim 1, wherein a part (122) of the first liquid stream (119) is fed to a H.sub.2 stripper (160) to remove H.sub.2 to form a second liquid stream comprising propylene and the comonomer.

7. The process according to claim 6, wherein at least part of the second liquid stream is fed to the reactor as a part of the H.sub.2 poor quench liquid (101).

8. The process according to claim 6, wherein at least part of the second liquid stream is vaporized and fed as a part of the H.sub.2 poor bottom gas (102).

9. The process according to claim 1, wherein the reactor off-gas is fed to a cyclone from which polymer particles are carried back to the reactor by means of the H.sub.2 poor gas stream (102).

10. The process according to claim 1, wherein the catalyst system is a Ziegler-Natta catalyst system, wherein the Ziegler-Natta catalyst system comprises a procatalyst, a co-catalyst and optionally an external electron donor, wherein the procatalyst is obtained by a process comprising the steps of Step A) providing or preparing a compound R.sup.4.sub.zMgX.sup.4.sub.2-z wherein R.sup.4 is independently selected from linear, branched or cyclic hydrocarbyl group independently selected from alkyl, alkenyl, aryl, aralkyl, or alkylaryl groups, and one or more combinations thereof; wherein said hydrocarbyl group is substituted or unsubstituted, and optionally contain one or more heteroatoms; X.sup.4 is independently selected from the group consisting of fluoride (F—), chloride (Cl—), bromide (Br—) or iodide (I—); z is in a range of larger than 0 and smaller than 2, being 0<z<2; Step B) contacting the compound R.sup.4.sub.zMgX.sup.4.sub.2-z with a silane compound Si(OR.sup.5).sub.4-nR.sup.6).sub.n to give a first intermediate reaction product, being a solid Mg(OR.sup.1).sub.xX.sup.1.sub.2-x wherein R.sup.1, R.sup.5 and R.sup.6 are each independently selected from linear, branched or cyclic hydrocarbyl group independently selected from alkyl, alkenyl, aryl, aralkyl, alkoxycarbonyl or alkylaryl groups, and one or more combinations thereof; wherein said hydrocarbyl group is substituted or unsubstituted, and optionally contain one or more heteroatoms; X.sup.1 is independently selected from the group consisting of fluoride (F—), chloride (Cl—), bromide (Br—) or iodide (I—); n is in range of 0 to 4, preferably n is from 0 up to and including 1; z is in a range of larger than 0 and smaller than 2, being 0<z<2; x is in a range of larger than 0 and smaller than 2, being 0<x<2; Step C) activating said solid support, comprising two sub steps: Step C1) a first activation step by contacting the first intermediate reaction product obtained in step B) with at least one first activating compound being a metal alkoxide compound of formula M.sup.1(OR.sup.2).sub.v-w(OR.sup.3).sub.w or M.sup.2(OR.sup.2).sub.v-w(R.sup.3).sub.w; wherein: M.sup.1 is a metal selected from the group consisting of Ti, Zr, Hf, Al or Si; M.sup.2 is a metal being Si; v is the valency of M.sup.1 or M.sup.2 and w is smaller than v; R.sup.2 and R.sup.3 are each a linear, branched or cyclic hydrocarbyl group independently selected from alkyl, alkenyl, aryl, aralkyl, alkoxycarbonyl or alkylaryl groups, and one or more combinations thereof; wherein said hydrocarbyl group is substituted or unsubstituted, and optionally contain one or more heteroatoms; and a second activating compound being an activating electron donor; and Step C2) a second activation step by contacting the activated solid support obtained in step C1) with an activating electron donor; to obtain a second intermediate reaction product; Step D) reacting the second intermediate reaction product obtained step C2) with a halogen-containing Ti-compound, optionally an activator prior to or simultaneous with the addition of an internal donor, and at least one internal electron donor to obtain said procatalyst.

11. The process according to claim 1, wherein the reactor is provided with two reaction zones that are arranged subsequent to each other in the downstream direction of the process, wherein a first reaction zone (110) of said two reaction zones is fed with the H.sub.2 poor quench liquid (101) and the H.sub.2 poor bottom gas (102), and a second reaction zone (120) of said two reaction zones is fed with the H.sub.2 rich quench liquid (103) and the H.sub.2 rich bottom gas (104).

12. The process according to claim 1, wherein the reactor is provided with three reaction zones that are arranged subsequent to each other in the downstream direction of the process, wherein a first reaction zone (110) of said three reaction zones is fed with the H.sub.2 poor quench liquid (101) and the H.sub.2 poor bottom gas (102), a second reaction zone (120) of said three reaction zones is fed with either i) the H.sub.2 poor quench liquid (101) and the H.sub.2 rich bottom gas (104) or ii) the H.sub.2 rich quench liquid (103) and the H.sub.2 poor bottom gas (102), and a third reaction zone (130) of said three reaction zones is fed with the H.sub.2 rich quench liquid (103) and the H.sub.2 rich bottom gas (104).

13. Setup assembly for the production of polypropylene comprising at least: a horizontal stirred reactor (100) comprising an agitated bed for forming polymer particles with at least two reaction zones, a plurality of liquid feed ports (111, 112) that are subsequently arranged along a top side of the reactor above the agitated bed, the plurality of liquid feed ports comprising a first set of the liquid feed ports (111) and a second set of the liquid feed ports (112) arranged subsequent to the first set of the liquid feed ports in a downstream direction of the process, and a plurality of gas feed ports (114, 115) that are subsequently arranged along a bottom side of the reactor below the agitated bed, the plurality of gas feed ports comprising a first set of gas feed ports (114) and a second set of gas feed ports (115) arranged subsequent to the first set of gas feed ports in the downstream direction of the process a plurality of off-gas ports (116) arranged along a top side of the reactor above the agitated bed in a downstream direction of the process a recycle loop comprising: a condenser (150) connected to the horizontal stirred reactor (100) by the plurality of off-gas ports (116), and a separator (140) connected to the condenser by a gas liquid mixture line (118) and to the horizontal stirred reactor by a first liquid stream line (119) to the second set of the liquid feed ports (112), and a first gas stream line (121) to the second set of gas feed ports (115).

14. Setup assembly according to claim 13, further comprising a stripper (160) configured to remove at least H.sub.2 and connected to to the separator (140) through a liquid stream line (122) which is a part of the first liquid stream (119) to the first set of the liquid feed ports (111) of horizontal stirred reactor (100) through a poor H.sub.2 line configured to carry on a H.sub.2 poor quench liquid produce by the stripper, and to the condenser (150) through a rich H.sub.2 line (123).

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) The invention is now elucidated referring to the drawings in which:

(2) FIGS. 1a to 4b show a schematic representation of examples of a system for carrying out the process of the invention comprising a reactor with two reaction zones;

(3) FIGS. 5a to 6b show a schematic representation of further examples of a system for carrying out the process of the invention comprising a reactor with two reaction zones and a stripper column;

(4) FIGS. 7a to 10b show a schematic representation of further examples of a system for carrying out the process of the invention comprising a reactor with three reaction zones and a stripper column;

(5) FIG. 11a to 12j show a graph comprising Mass fraction (wt %) and Melt flow Index MFI (dg/min) over Total Production (%) for each examples.

(6) FIGS. 13 and 14 show a graph comprising Mass fraction (wt %) and Melt flow Index MFI (dg/min) over Total Production (%) for prior art setup assembly without means to control a concentration gradient of comonomer.

EXAMPLES

(7) The following examples are performed under the same conditions and parameters, in order that the only variable is the locations where comonomer is to be fed in the system and it nature.

(8) For the non-limiting example 1a to 10a, the comonomer is ethylene and for the non-limiting example 1b to 10b, the comonomer is 1-hexene.

Example 1a

(9) FIG. 1a shows a schematic representation of a non-limiting example of a system for carrying out the process of the invention, in which a reactor 100 consisting of a first reaction zone 110 and a second reaction zone 120.

(10) In this embodiment, the comonomer chosen from a group comprising ethylene and C4-C12 α-olefin is ethylene.

(11) Fresh ethylene is fed to the reactor by feeding the fresh ethylene directly to the reactor as a part of the H.sub.2 poor bottom gas 102.

(12) The reactor off gas 117 is condensed by a condenser 150 to provide a gas-liquid mixture 118, whish fed a separator 140 where fresh propylene is added.

(13) The separator 140 allows a separation of the gas-liquid mixture 118 into a first liquid stream 119 and a first gas stream 121.

(14) The first gas stream 121 is mixed with additional H.sub.2 and the obtained H.sub.2 rich bottom gas 104 is fed to the second reaction zone 120.

(15) Thus, in this embodiment, the first reaction zone 110 is fed with the H.sub.2 poor quench liquid 101 and the H.sub.2 poor bottom gas 102.

(16) The copolymer prepared in this first reaction zone 110 has a high molecular weight.

(17) The second reaction zone 120 is fed with the H.sub.2 rich quench liquid 103 and the H.sub.2 rich bottom gas 104.

(18) The copolymer prepared in this second reaction zone 120 has a low molecular weight.

(19) The ethylene concentration would be relatively flat over the reactor as a part of ethylene present in the reactor off gas 117 will be send by the separator 140 in the first gas stream 121 due to this low molecular weight.

Example 1b

(20) FIG. 1b shows a similar setup that the FIG. 1a In which the comonomer chosen from a group comprising ethylene and C4-C12 α-olefin is 1-hexene.

(21) The 1-hexene concentration would be decreasing over the reactor as 1-hexene is only fed as part of the H.sub.2 poor bottom liquid 101.

Example 2a and 2b

(22) In another non-limitative embodiment shown by FIGS. 2a and 2b, fresh comonomer could be add in the system through the separator 140.

(23) Due to the low molecular weight of ethylene, the separator will send most part of it in the first gas stream 121, conversely, a C4-C12 α-olefin will be send to first liquid stream 119.

(24) In FIG. 2a configuration, ethylene concentrations would be relatively higher in low molecular weight distribution part.

(25) In FIG. 2b configuration, 1-hexene concentrations would be relatively higher in low molecular weight distribution part.

Example 3a and 3b

(26) In another non-limitative embodiment shown by FIGS. 3a and 3b, fresh comonomer could be add in the system after the separator 140, in the first gas stream 121 when the comonomer is ethylene, in the first liquid stream 119 when the comonomer is a C4-C12 α-olefin.

(27) The profile of the copolymer obtain by this process will look like to the one obtain when comonomer is added in the system through the separator 140.

(28) In FIG. 3a configuration, ethylene concentrations would be relatively higher in low molecular weight distribution part.

(29) In FIG. 3b configuration, 1-hexene concentrations would be relatively higher in low molecular weight distribution part.

Example 4a and 4b

(30) In another non-limitative embodiment shown by FIGS. 4a and 4b, which is the combination of the embodiments shown in FIGS. 1 and 2.

(31) The split feed of the fresh 1-hexene or ethylene allows to give a flat profile of 1-hexene concentration in the weight distribution and an intermediate profile for ethylene than the one obtain in the embodiments described by FIGS. 1 and 2.

Example 5a and 5b

(32) In another non-limitative embodiment shown by FIGS. 5a and 5b, a schematic representation of a non-limiting example of a system for carrying out the process of the invention, similar to the one describe in FIGS. 1a and 1b, and comprising an additional stripper column 160 configured to remove at least H.sub.2 and connected: to the separator 140 through a liquid stream line 122 comprising a part of the first liquid stream line 119, to the first set of the liquid feed ports 111 of horizontal stirred reactor 100 through a poor H.sub.2 liquid stream line which is configured to carry on a H.sub.2 poor quench liquid produce by the stripper, and to the condenser 150 through a rich H.sub.2 stream line 123.

(33) In this configuration, the stripper allows for high H.sub.2 lean quench availability.

(34) However, in the embodiment describe by FIG. 5a, a significate amount of ethylene due to its low molecular weight will be remove by the stripper into the rich H.sub.2 streamline 123, and will continue its pass to the separator, which will send most part of it in the first gas stream 121. Therefor the ethylene concentration should be relatively flat.

(35) Regarding FIG. 5b, the stripper will reintroduce already present 1-hexene as a part of the H.sub.2 poor bottom liquid 101. Therefor the 1-hexene concentration will be higher in the first part of the reactor and decreasing toward the end of the reactor.

(36) In each embodiment, depending of the operation parameter, a valve will control the repartition of the first liquid stream line 119 between line 122 and 103. Therefore, it will influence the gradient of the comonomer.

Example 6a and 6b

(37) In another non-limitative embodiment shown by FIGS. 6a and 6b comprising a setup Identical to the one in FIGS. 5a and 5b, fresh comonomer are added in the system after the separator 140, in the first gas stream 121 when the comonomer is ethylene (FIG. 6a), in the first liquid stream 119 when the comonomer Is a C4-C12 α-olefin (FIG. 6b).

(38) The profile of the copolymer obtain by this process will look like to the one obtain when comonomer is added in the system through the separator 140.

(39) In FIG. 6a configuration, ethylene concentrations would be relatively higher in low molecular weight distribution part 120 and increasing toward the end of the reactor.

(40) In FIG. 6b configuration, 1-hexene concentrations would be relatively flat in the reactor. However, the repartition of the first liquid stream line 119 between lines 122 and 103 will be able to control the concentration gradient. The concentration will be higher in the first zone of the majority of the stream is redirected trough the stripper, and will be lower if the majority of the stream is redirected trough the H.sub.2 rich quench liquid 103.

Example 7a to 10b

(41) In other non-limitative embodiments shown by FIG. 7a to 10b, the system for carrying out the process of the invention comprise a reactor 100 consisting of a first reaction zone 110, a second reaction zone 120 and a third reaction zone 130 arranged subsequent to each other in the downstream direction of the process, wherein a first reaction zone of said three reaction zones is fed with the H.sub.2 poor quench liquid and the H.sub.2 poor bottom gas, a second reaction zone of said three reaction zones is fed with either i) the H.sub.2 poor quench liquid and the H.sub.2 rich bottom gas as show in the figure, or ii) the H.sub.2 rich quench liquid and the H.sub.2 poor bottom gas (embodiments not illustrated by the said example), and a third reaction zone of said three reaction zones is fed with the H.sub.2 rich quench liquid and the H.sub.2 rich bottom gas.

(42) The rest of the setup is similar to the one illustrated in FIG. 5a to 5b.

(43) A reactor off-gas 117 comprising H.sub.2, propylene and the comonomer is recovered from the reactor through a set of off-gas ports 116.

(44) The reactor off-gas 117 is condensed by a condenser 150 to provide a gas-liquid mixture 118, which is fed to a separator 140.

(45) The separator 140 can be also fed with fresh propylene.

(46) The separator 140 provides a first liquid stream 119 comprising essentially propylene and the commoner as well as H.sub.2 dissolved in the liquid mixture of propylene and a first gas stream 121 comprising essentially H.sub.2, propylene and ethylene when it is used.

(47) The first gas stream 121 is mixed with additional H.sub.2 and the obtained H.sub.2 rich bottom gas 104 is fed to the third reaction zone 130.

(48) The first liquid stream 119 is fed to the second reaction zone 120 and the third reaction zone 130 through the second set of liquid port 112, as the H.sub.2 rich quench liquids 103.

(49) Thus, in this embodiment, the first reaction zone 110 is fed with the H.sub.2 poor quench liquid 101 and the H.sub.2 poor bottom gas 102. The copolymer prepared in this first reaction zone 110 has a high molecular weight.

(50) The third reaction zone 130 is fed with the H.sub.2 rich quench liquid 103 and the H.sub.2 rich bottom gas 104. The copolymer prepared in this first reaction zone 110 has a low molecular weight.

(51) The second reaction zone 120 is fed with the H.sub.2 rich quench liquid 103 and the H.sub.2 poor bottom gas 102. The copolymer prepared in this second reaction zone 120 has a molecular weight between those made in the first and the third reaction zones 110, 130.

(52) In FIG. 7a, since fresh ethylene is fed directly to the first reaction zone 110 and the second reaction zone 120 as part of the H.sub.2 poor bottom gas 102, the third reaction zone 130 receives ethylene only from the reactor off-gas.

(53) In FIG. 7b, since fresh 1-hexene is fed directly to the first reaction zone 110 as the H.sub.2 poor quench liquid 101, the second and the third reaction zones 120 and 130 receive 1-hexene only from the reactor off-gas.

(54) In FIG. 8a, since fresh ethylene is fed in the system through the separator 140 and due to Its low molecular weight a largest portion will be Introduce Into the third reaction zone 130 as H.sub.2 rich bottom gas 104. A very small amount dissolved in the liquid mixture will be introduce into the second and third reaction zone as a part H.sub.2 rich quench liquid 103.

(55) The first reaction zone 110 will only contain trace of ethylene as the majority of it will be remove by the stripper in the same time that H.sub.2. Thus, the first part of the reactor should have a very low concentration, but the concentration will be increasing drastically toward the end of the reactor.

(56) In FIG. 8b, since fresh 1-hexene is fed in the system through the separator 140 and will be introduce into the first liquid stream 119.

(57) In this embodiment, due to the presence of the stripper loop alimented by a portion of the first liquid stream 119, very parts of the reactor will be fed.

(58) Therefore, the repartition of the first liquid stream 119 in to the H.sub.2 rich quench liquid 103 and the liquid stream line 122 will determine the concentration profile of 1-hexene through the entire reactor. In an embodiment no illustrated, the absence of a stripper loop will allow to have higher concentration in the second and third reaction zone (as in FIGS. 3b and 4b).

(59) In FIG. 9a, the fresh ethylene is fed directly to the third reaction zone 130 as part of the H.sub.2 rich bottom gas 104. The second reaction zone 120 will only receive a very small amount of ethylene coming from the small portion dissolved in the liquid mixture 119 issue from the reactor off-gas 117. As in FIG. 8a, the first reaction zone will only contain minimal trace of ethylene and the concentration will be increasing drastically toward the end of the reactor.

(60) In the embodiment illustrated in FIG. 9b, fresh 1-hexene is fed in the system only as a part of the first liquid stream 119. The concentration profile will be similar to the one in FIG. 8b.

(61) In FIG. 10a, the fresh ethylene is fed directly as a part of the H.sub.2 poor bottom gas 102 and as a part of the H.sub.2 rich bottom gas 104, the concentration should be flat in the two first part of the reactor but Increasing in the last part of the reactor due to the recycling of the a reactor off-gas and the stripper loop. Indeed, due to the low molecular weight of ethylene, the majority of the ethylene containing in the reactor off-gas 117, will be reintroduce only as a part of the H.sub.2 rich bottom gas 104.

(62) In FIG. 10b, the fresh 1-hexene Is fed directly as a part of the H.sub.2 poor quench liquid 101 and as a part of the H.sub.2 rich quench liquid 103. Therefore the concentration 1-hexene of would be relatively flat in the reactor.

(63) However, the repartition of the first liquid stream line 119 between lines 122 and 103 will be able to control the concentration gradient. The concentration will be higher in the first zone of the majority of the stream is redirected trough the stripper, and will be lower if the majority of the stream is redirected trough the H.sub.2 rich quench liquid 103.

(64) In addition, in non-limitative embodiments of the invention (non-illustrated by the figures) and mentioned above, a configuration with a reactor with three reaction zones and without a stripper loop is possible.

(65) Mass Fraction (Wt %) and Melt Flow Index MFI (Dg/Min) Over Total Production (%) Graphs

(66) The following graphs refer to the example 1a to 10b, performed under the same operational parameters; the only variable was the localization of the fresh comonomer feeding.

(67) The FIGS. 11a to 11j corresponding to FIG. 1a to 10a, and the FIGS. 12a to 12j corresponding to FIG. 1b to 10b.

(68) In addition, the FIGS. 13 and 14 are related to prior art setup assembly wherein no control gradient can perform. In those embodiments, the comonomer concentration can only go crescendo.

(69) With the setup assembly for the production of polypropylene according to the invention, those graphs show that the gradient of comonomer can be control and therefor, new grade of polypropylene can be produce with specific melt flow index and new properties.

LIST OF REFERENCE SIGNS

(70) 100 an horizontal stirred reactor 101 H.sub.2 poor quench liquid 102 H.sub.2 poor bottom gas 103 H.sub.2 rich quench liquid 104 H.sub.2 rich bottom gas 110 a first reaction zone 111 a first set of the liquid feed ports 112 second set of the liquid feed ports 114 a first set of gas feed ports 115 a second set of gas feed ports 116 off-gas ports 117 a reactor off-gas 118 a gas liquid mixture line 119 a first liquid stream line 120 a second reaction zone 121 a first gas stream 122 a part of the first liquid stream 119 123 a rich H.sub.2 line 130 a third reaction zone 140 a separator 150 a condenser 160 a stripper column 116 off-gas ports